Handbook of Texas Online
- Current and historical information about Marion County.
- http://www.tsha.utexas.edu/handbook/online/articles/MM/hcm2.html

The Political Graveyard: Marion County, Tex.
- Information about politicians that lived or died in the county.
- http://www.politicalgraveyard.com/geo/TX/MP.html

Marion County Chamber of Commerce
- Jefferson, Texas area information. Includes attractions, lodging, postcards, dining, business directory, and calendar of events.
- http://www.jefferson-texas.com/

Amphibians and Reptiles in Marion County
- Texas Cooperative Wildlife Collection list of species found in the county.
- http://wfscnet.tamu.edu/tcwc/checklist/MARIO155.HTM